Hello,
Quick introduction! I’m Dwayne and new to blender and this forum.
This pig made in blender shows inverted faces in unreal engine. How can I solve this problem?
Unreal engine
Blender render
i’m not fully sure but i think this may be an isue with you’re normals. Most game engines only show the front face of a mesh and not the back. You will need to re-calculate your’e normals in blender before you export.
To do this, go into edit mode, select all verts (or just the ones that are effected) and press ctrl+n.
blender wiki page about normals - http://wiki.blender.org/index.php/Doc:2.6/Manual/Modeling/Meshes/Editing/Faces#Recalculate_Normals
Thank you so much Jamie! This solved my problem.
no problem mate 
glad i could help